1. Field of the Invention
The present invention relates to a navigation apparatus and navigation information calculation method, and is preferably applied to a car navigation apparatus mounted on a vehicle, for example.
2. Description of Related Art
Generally, a car navigation apparatus receives from a Global Positioning System (GPS) satellite a GPS signal and then calculates the position of a vehicle, which is then displayed. In addition, as disclosed in Patent Document 1 (see Jpn. Pat. Laid-open Publication No. 2004-138553), while not receiving the GPS signal due to the vehicle running inside a tunnel or the like, the car navigation system calculates, by using an acceleration sensor, the vehicle's acceleration in the direction of movement and then estimates the speed of the vehicle based on the calculated acceleration. The car navigation system can therefore display the current position of the vehicle, estimated based on the vehicle's speed, even when the vehicle does not receive the GPS signal.